SALT,  GYPSUM,  AND  PETROLEUM  IN  TRANS-PECOS  TEXAS. 
By  G.  B.  Richardson. 
INTRODUCTION. 
In  the  summer  of  1903  a  rapid  reconnaissance  was  made  of  that 
part  of  trans-Pecos  Texas  which  lies  north  of  the  Texas  and  Pacific 
Railway,  the  primary  object  being  to  examine  conditions  of  occur- 
rence of  underground  water.0  The  opportunity  was  taken  to  note 
deposits  of  salt,  petroleum,  gypsum,  and  sulphur  in  this  little-known 
region,  and  the  fragmentary  facts  observed  are  here  recorded.  The 
region  is  so  little  known  that  a  brief  description  of  the  topography 
and  stratigraphy  of  that  part  of  it  in  which  these  deposits  occur  is 
also  given. 
TOPOGRAPHY. 
The  accompanying  sketch  map  b  (PL  IV)  illustrates  the  general 
occurrence  of  the  deposits  to  be  described,  which  are  situated  in  east- 
ern El  Paso  and  northern  Reeves  counties.  This  area  lies  partly  in 
the  Great  Plains  and  partly  in  the  Cordilleras,  the  dividing  line  be- 
tween the  counties  marking  the  approximate  boundary  of  the  physio- 
graphic provinces.  The  dominant  topographic  feature  of  the  region 
is  the  highland  belt  comprising  the  Guadalupe-Delaware  Mountains, 
that  extend  in  a  northwest-southeast  direction,  separating  the  low- 
lands of  Toyah  basin  on  the  east  from  Salt  basin  on  the  west. 
The  Guadalupe-Delaware  Mountains  constitute  an  eastward-slop- 
ing monocline  and  present  a  steep  scarp  to  the  Salt  basin.  This 
escarpment  is  especially  prominent  in  the  northern  part  of  the  area, 
where  it  rises  almost  5,000  feet  above  the  adjacent  plain.  Southward 
the  difference  in  elevation  decreases  to  about  1,000  feet. 
The  Guadalupe  Mountains  extend  into  Texas  from  New  Mexico, 
crossing  the  State  line  about  45  miles  west  of  Pecos  River.     Here  the 
a  In  cooperation  with  the  University  of  Texas  Mineral  Survey. 
b  For  more  detailed  map,  see  Richardson,  G.  B.,  Report  of  a  reconnaissance  in  trans- 
Pecos  Texas :  Bull.  No.  9,  University  of  Texas  Mineral  Survey,  1904. 
573 
